Add implement for FreeBSD amd64

A clone from serial_linux.go

Fixes tarm#54

serial_freebsd.go

@@ -0,0 +1,150 @@
+// +build freebsd,!cgo
+
+package serial
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+func openPort(name string, baud int, databits byte, parity Parity, stopbits StopBits, readTimeout time.Duration) (p *Port, err error) {
+	var bauds = map[int]uint32{
+		50:     syscall.B50,
+		75:     syscall.B75,
+		110:    syscall.B110,
+		134:    syscall.B134,
+		150:    syscall.B150,
+		200:    syscall.B200,
+		300:    syscall.B300,
+		600:    syscall.B600,
+		1200:   syscall.B1200,
+		1800:   syscall.B1800,
+		2400:   syscall.B2400,
+		4800:   syscall.B4800,
+		9600:   syscall.B9600,
+		19200:  syscall.B19200,
+		38400:  syscall.B38400,
+		57600:  syscall.B57600,
+		115200: syscall.B115200,
+		230400: syscall.B230400,
+		460800: syscall.B460800,
+		921600: syscall.B921600,
+	}
+
+	rate := bauds[baud]
+
+	if rate == 0 {
+		return nil, fmt.Errorf("invalid baud rate %d", baud)
+	}
+
+	f, err := os.OpenFile(name, syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_NONBLOCK|syscall.O_EXCL, 0666)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		if err != nil && f != nil {
+			f.Close()
+		}
+	}()
+
+	// Base settings
+	cflagToUse := syscall.CREAD | syscall.CLOCAL | rate
+	switch databits {
+	case 5:
+		cflagToUse |= syscall.CS5
+	case 6:
+		cflagToUse |= syscall.CS6
+	case 7:
+		cflagToUse |= syscall.CS7
+	case 8:
+		cflagToUse |= syscall.CS8
+	default:
+		return nil, ErrBadSize
+	}
+	// Stop bits settings
+	switch stopbits {
+	case Stop1:
+		// default is 1 stop bit
+	case Stop2:
+		cflagToUse |= syscall.CSTOPB
+	default:
+		// Don't know how to set 1.5
+		return nil, ErrBadStopBits
+	}
+	// Parity settings
+	switch parity {
+	case ParityNone:
+		// default is no parity
+	case ParityOdd:
+		cflagToUse |= syscall.PARENB
+		cflagToUse |= syscall.PARODD
+	case ParityEven:
+		cflagToUse |= syscall.PARENB
+	default:
+		return nil, ErrBadParity
+	}
+	fd := f.Fd()
+	vmin, vtime := posixTimeoutValues(readTimeout)
+	t := syscall.Termios{
+		Iflag:  syscall.IGNPAR,
+		Cflag:  cflagToUse,
+		Cc:     [20]uint8{syscall.VMIN: vmin, syscall.VTIME: vtime},
+		Ispeed: rate,
+		Ospeed: rate,
+	}
+
+	// from https://fossies.org/linux/cdrtools/include/schily/termios.h
+	// in FreeBSD TCSETS = syscall.TIOCSETAW
+	if _, _, errno := syscall.Syscall6(
+		syscall.SYS_IOCTL,
+		uintptr(fd),
+		uintptr(syscall.TIOCSETAW),
+		uintptr(unsafe.Pointer(&t)),
+		0,
+		0,
+		0,
+	); errno != 0 {
+		return nil, errno
+	}
+
+	if err = syscall.SetNonblock(int(fd), false); err != nil {
+		return
+	}
+
+	return &Port{f: f}, nil
+}
+
+type Port struct {
+	// We intentionly do not use an "embedded" struct so that we
+	// don't export File
+	f *os.File
+}
+
+func (p *Port) Read(b []byte) (n int, err error) {
+	return p.f.Read(b)
+}
+
+func (p *Port) Write(b []byte) (n int, err error) {
+	return p.f.Write(b)
+}
+
+// Discards data written to the port but not transmitted,
+// or data received but not read
+func (p *Port) Flush() error {
+	const TCFLSH = 0x540B
+	_, _, err := syscall.Syscall(
+		syscall.SYS_IOCTL,
+		uintptr(p.f.Fd()),
+		uintptr(TCFLSH),
+		uintptr(syscall.TCIOFLUSH),
+	)
+	return err
+}
+
+func (p *Port) Close() (err error) {
+	return p.f.Close()
+}